Pupa

Utsutsu and Yume Hasegawa, siblings, live with each other since their parents abandoned them. The siblings are drawn to red butterflies that have appeared in their world. These butterflies signal the emergence of the Pupa virus, which causes grotesque transformations in those infected. Utsutsu and Yume are affected differently: Yume becomes a monstrous creature with a desire for human flesh, while Utsutsu gains regenerative powers. Utsutsu is determined to keep his promise to protect his sister despite the danger she poses.